University of Tennessee Turfgrass Science and Management Team’s resources offer assistance to Extension agents, landscaping professionals, athletic and recreational field managers, master gardeners, public gardens directors, golf course superintendents, homeowners, and other enthusiasts working with turfgrass in Tennessee.
Download the Mobile Weed Manual below to explore weed management solutions at your fingertips.
Mobile Weed Manual
The Mobile Weed Manual was prepared to assist turfgrass managers with developing effective weed management programs. The manual can be dowloaded to a device or accessed online at mobileweedmanual.com.
Turfgrass Publications
Selecting a species and variety that are adapted to the climate and soil of a particular site is a very important part of a comprehensive turfgrass management plan. The goal is to plant an adapted turfgrass capable of providing the desired quality at a reasonable maintenance intensity level and cost. The cost of maintaining a turf through the years is reduced by purchasing the right turfgrass. The long-term, seed or sod bargain is not always the lowest priced turfgrass variety.Turfgrasses usually grow best in full sun and in nutrient-rich, well-drained soils.
Topography and soils of Tennessee influence how turfgrasses perform. Cool-season turfgrasses are usually well adapted in East Tennessee which is mostly mountainous, with broad, fertile valleys. Here, soils were formed from limestone, sandstone or shale. The rolling hills of the Central Basin in middle Tennessee reach an elevation of 800 feet or more. Both warm- and cool-season turfgrasses are maintained in limestone-based, phosphorus-rich soils of the Central Basin. The Highland Rim surrounding the Central Basin is composed of hills often reaching an elevation of 1,000 feet or more. Cool-season turfgrasses usually perform very well on the Highland Rim. Bermudagrass and Zoysia are the predominate turfgrass species maintained at elevations approaching sea level in southwest Tennessee.
Extension Publications on this Subject:
W 159-A: Bermudagrass
W 159-B: Bluegrasses
W 159-C: Centipedegrass
W 159-D: Creeping Bentgrass
W 159-E: Fescues
W 159-F: Ryegrasses
W 159-G: St. Augustinegrass
W 159-H: Zoysia
Some turfgrasses are established from seed, others, from sod, plugs, or harvested segments of above or below-ground runners referred to as sprigs. Regardless of the method of establishment, site preparation, timing and post-planting care usually determine whether turfgrasses survive. Since bluegrasses, fescues and ryegrasses grow best from 60 – 75 degrees Fahrenheit, late August to mid-October is an ideal time to plant seed of these cool-season turfgrasses. Although wet, rainy weather may make soil preparation difficult, fescues and ryegrasses are also seeded in late winter or early spring.
Kentucky bluegrass seed germinates slowly compared to fescues and ryegrasses, and poorly developed seedlings resulting from spring seeding may be killed by hot, dry weather in summer. Temperatures from 80 – 95 degrees Fahrenheit promote the growth of bermudagrass, centipedegrass, St. Augustinegrass and Zoysia. Seed, plugs or sprigs of these warm-season species should be planted between May 1 and June 30. Sod of cool- or warm-season turgrasses can be installed any time of year, as long as the planting bed is not frozen. However, several weeks or months may be required before a newly sodded turf can withstand traffic.
Extension Publications on this Subject:
W 160-A: Preparing to Plant
W 160-B: Seeding
W 160-C: Sodding and Plugging
W 160-D: Sprigging
W 160-E: Turfgrass Seed
W 160-F: When to Plant Turfgrass
Turfgrasses require routine maintenance. Mowing, fertilization and irrigation are primary maintenance practices most often needed to keep turfs healthy. Mowing maintains uniform plant height, suppresses weeds and stripes the turf. Turfs are fertilized to provide nutrients that would otherwise limit plant growth. An application of lime may be necessary to neutralize soil acids and supply plants with calcium and magnesium. Actively growing turfgrasses often contain more than 70 percent water and use from 1/10 to 3/10 inch of water each day. Turfs are irrigated to prevent severe drought stress and activate fertilizers, herbicides and insecticides.
Sometimes, turfs benefit from supplementary maintenance practices such as dethatching, mechanical aeration, topdressing and rolling. Turfs are dethatched to lift and remove excess organic matter from the soil surface. Core aerification loosens soil and speeds the flow of water into the turfgrass root zone. Broadcasting a shallow layer of soil or compost over a turf after core aerifying may smooth the surface and improve the soil’s biological activity. Turfgrass plants can be lifted from soil as it freezes and thaws during winter. A roller is used to press plants back into contact with soil.
Extension Publications on this Subject:
W 161-A: Basic Turfgrass Requirements
W 161-B: Cultivation
W 161-C: Developing a Turf Fertilization Plan
W 161-D: Essential Elements
W 161-E: Fertilizers
W 161-F: Irrigation
W 161-G: Liming
W 161-H: Mowers
W 161-I: Mowing
W 161-J: Overseeding Bermudagrass with Perennial Ryegrass
W 161-K: Predicting the Probability of a Freeze
W 161-L: Rolling
W 161-M: Thatch
W 161-N: Topdressing
Extension Publications on this Subject:
W 205: Controlling Winter Annual Broadleaf Weeds
W 147: Virginia Buttonweed (Diodia virginiana)
W 266: Ground Ivy (Glechoma hederacea)
W 267: White Clover (Trifolium repens)
W 399: Hairy Bittercress (Cardamine hirsuta)
W 404: Parsley Piert (Aphanes arvensis)
W 807: Wild Violets (Viola spp.)
Grassy Weed Control
W 203: Annual Bluegrass Control in Non-Overseeded Bermudagrass Turf
W 204: Annual Bluegrass Control in Overseeded Bermudagrass Turf
SP 642: Dallisgrass (Paspalum dilatatum)
W 170: Goosegrass (Eleusine indica)
W 146: Crabgrass (Digitaria spp.)
W 216: Star-of-Bethlehem (Ornithogalum umbellatum)
W 212: Wild Garlic (Allium vineale)
W 237: Bermudagrass Control in Tall Fescue and Zoysiagrass Turf
W 238: Weed Control During the Seeded Establishment of Cool Season Turfgrasses
W 239: Removing Overseeded Perennial Ryegrass from Bermudagrass Turf
W 243: Current Status of MSMA Use in Turf
W 260: Nutsedge and Kyllinga Species
W 808: Nimblewill (Muhlenbergia schreberi)
Herbicide
SP 707: Choosing the Right Herbicide
W 268: Herbicides For Use on Golf Course Putting Greens
SP 269: Weed Control in Centipedegrass (Eremochloa ophiuroides)
W 270: Safety of Herbicides Compared to Other Commonly Used Chemicals
W 294: Using Growing and Cooling Degree Day Accumulations to Maximize Herbicide Efficacy
D 5: Preemergence Herbicide Selection Following Winter Stress
W 827: Frequently Asked Questions: Glyphosate
Other
Common Mathematical Conversion Factors for Herbicide Calibration
W 192: Why Will My Weed Problem Not Go Away?
SP 242: Brush Control in Urban Landscapes
D 4: Testing Turf for Winterkill
Sooner or later, diseases, insects, extreme heat or cold, drought and saturated soils may severely damage turf. For example, each spring, Rhizoctonia fungi are responsible for patches of injured plants observed in bermudagrass, tall fescue and Zoysia. White grubs, the larvae of scarab beetles, feed on roots. Fescues and Kentucky bluegrass plants may die in summer when leaf temperatures reach 100 degrees Fahrenheit or more. Bermudagrass, centipedegrass, St. Augustinegrass and Zoysia are dormant and prone to low temperature injury in winter. Excessively dry soils resulting from extended periods of drought do not provide adequate amounts of water or essential nutrients. Too much water may accumulate on sites with poor surface or subsurface drainage. Roots of turfgrasses growing in saturated soils often die from a lack of oxygen.
Improper mowing, fertilization or pesticide application may also damage turf. Removing too many leaves when mowing severely reduces the amount of leaf surface exposed to sunlight. As a result turfgrasses may lose energy and be less able to compete with weeds such as crabgrass and goosegrass. Routine scalping results in poorly rooted turfs that are prone to drought and high or low temperature injury. Soils seldom provide plants with enough nitrogen, and may also be low in phosphorus and potassium. Turfs in need of fertilization are often thin and disease prone. However, applying too much fertilizer at one time can increase the salt concentration of the solution surrounding roots and cause plants to dehydrate and die. The mis-application of a fungicide, herbicide or insecticide is often toxic to turfgrasses as well as troublesome pests.
Weed Diagnostics Testing
The Weed Diagnostic Center offers services essential to management strategies.
Fresh plant samples, along with a submission form, should be mailed to:
UT Weed Diagnostics Center
Attention: Jose Vargas
112 Plant Biotechnology Building
2505 E J Chapman Drive
Knoxville, TN 37996
Bermudagrass
Plants will be cultured in a germination chamber until producing a minimum of 10 stolons with at least 4 nodes. Morphological characterization will include stolon internode length and diameter, leaf blade length and width, and leaf length:width ratio using digital calipers. In most cases, a report detailing the sample and control recommendations will be provided 4-7 weeks after sample submission.
An example summary report can be accessed here.
$349 per sample for Tennessee residents | $449 per sample for non-Tennessee residents
Molecular Resistance Confirmation
Plants will be cultured in a germination chamber and DNA will be extracted from plant tissue and analyzed for target site mutations associated with herbicide resistance. In most cases, individuals submitting a sample will receive a report detailing results that also provides control recommendations within 3 – 5 weeks of sample submission.
$2999 per sample for Tennessee residents | $3299 per sample for non-Tennessee residents
Rapid Resistance Screening
Plants will be established in agar culture using modified methods (Kaundun et al., 2011). When available, known resistant and susceptible lines of the same weed species will be established in agar as well. In the event a known resistant standard is not available for the weed submitted, samples will be screened with a known susceptible sample of the same species and exposed to a discriminatory rate of herbicide. A discriminatory rate of an herbicide of interest will be loaded into the agar and responses will be monitored. All diagnostic tests will be replicated 5 times.
At present, this test can only be used to screen for acetolactate synthase (ALS), for example trifloxysulfuron, dinitroaniline, for example prodiamine, and 5-enolpyruvylshikimate-3-phosphate synthase, for example glyphosate, inhibitor resistance. However, it will be adjusted to screen for resistance to other modes of action in the future.
Not all weed species can be tested using this rapid method. Please consult the WDC with specific questions about plant material to be tested.
An example summary report can be accessed here.
$649 per sample for Tennessee residents | $749 per sample for non-Tennessee residents
Traditional Whole Plant Resistance Screening
Plants will be cultured in a germination chamber in order to produce seeds for resistance screening. Samples will be seeded along with known resistant and susceptible standards and exposed to a discriminatory rate of a single herbicide. All tests will be replicated 3 times. In the event a known resistant standard is not available for the weed submitted, samples will be screened with known susceptible sample of the same species and exposed to a discriminatory rate of herbicide.
In most cases, a report detailing results and providing control recommendations will be provided 16 – 20 weeks after sample submission.
$1499 per sample for Tennessee residents | $1599 per sample for non-Tennessee residents
Basic Identification
Weeds will be identified based on morphological and botanical characteristics.
In most cases, a report detailing the sample and control recommendations will be provided 7 – 10 days after receipt (depending on the quality and health of the sample submitted).
An example summary report can be accessed here.
$29 per sample for Tennessee residents | $39 per sample for non-Tennessee residents
Molecular Identification
Weeds that cannot be identified via traditional means will be recommended for molecular weed identification using internally transcribed spacer (ITS) DNA. Genomic DNA will be extracted from plant tissues and used as a template for amplification of the ITS region. Amplified products will be purified and sent for sequencing. Sequences will be entered in a Blast search at GenBank and identified by sequence identity (≥ 98%). The Weed Diagnostic Center will maintain an ITS sequence and DNA library of weeds for future reference and study.
In most cases, a report detailing the sample and control recommendations will be provided 2 – 3 weeks after receipt.
$699 per sample for Tennessee residents | $799 for non-Tennessee residents